If you filter data on a Summary screen the system will automatically lock the filters in place, the columns where you have entered a filter are highlighted in orange to make it easy to see.
The filters will remain in place until you either remove them or change your view - the filters are stored at a User level, so if you enter a filter then other Users will not be affected. If you change your view, for example from 'All Contracts' to 'My Contracts' then the filters will be removed as the other view may not contain the same field columns.
If you move from feature to feature, say Contract to People and back again or open a record, when you return to the original Summary screen that had the filters, they will still be in place.
Fig 1 - Padlock to freeze filter values
You can remove individual column filters by either deleting the actual text or use the small 'x' icon in the Search block.
To remove all the filters across all the column at once, use the orange [x] button to the left of the filter block.